Parasyte -The Origin-
by epic72435
Summary: Parasytes. What are they? Where do they come from? They had to have come from somewhere. The answers to these questions are explained in this prequel story revolving around Seijū Niyani, a mechanical engineer who lives in a large apartment with his brother, Kussaku Niyani; that is, when Kussaku isn't out on an excavation.
1. Chapter 1

"Hey! Kussaku! We just hit a jackpot!" Hibiki called out. _They what—?!_ Kussaku's heart jumped, excitement flowing through his veins. He turned towards Hibiki, who had stopped outside the trailer. After quickly pulling on a coat over his tank top and pulling on a beanie and scarf, Kussaku threw open the door, letting the cold wind blow inside.

"What'd you guys find?" Kussaku asked enthusiastically, barely containing his excitement.

"You'll have to see it to believe it! Come on!" Hibiki said. He ran off towards the tunnel; Kussaku took off after him, nearly slipping on the snow as they went downhill towards the tunnel entrance. Hibiki entered the hole that served as the entrance to the rugged, dirt-filled tunnel, stepping over a steel pickaxe. Kussaku quickly followed. The tunnel was much warmer; Kussaku pulled off his beanie and his scarf, shoving them in his coat. After a bit of jogging, they made it to the end of the tunnel, which opened up into a much larger space. Kussaku exited the tunnel, nearly hitting his head on a gas lamp. Hibiki stopped. _...Whoa!_

A large hot spring spread out in front of him, bubbles and steam rising from the water. Surrounding the hot spring were countless fossils ingrained in the rock walls, the bones clearly visible. _Amazing...! This...this is exactly what we've been looking for!_ Kussaku's eyes shone with excitement. He finally bubbled over.

"Th-this is...amazing...! Amazing!" Kussaku softly rubbed his gloved hands over one of the fossils.

"That's not all," Ayumu pointed out from the other side of the spring. _It's not?!_ Kussaku turned, looking at him. The other excavators were all standing next to Ayumu.

"You won't believe this," Hibiki whispered. The two of them ran over to Ayumu. He pointed at the spring. Kussaku gazed into the water. _...What on Earth?_ Something blue-green seemed to be glowing at the bottom; it was as though the entire bottom of the spring was coated in fluorescent paint.

"...What...is it?" Kussaku stuttered, amazed.

"We're not sure yet. We wanted to wait for you to get here, since...well, you're our boss," Yumiko, another excavator, revealed.

"Well, I'm here now! What're you waiting for?!" Kussaku exclaimed excitedly.

"Al-RIGHT! Let's see what we've got here..." Ayumu said, reaching into the water with a long pole. He poked the bottom. "It's kinda...soft, almost! And it's loose!"

"Here you go." Yumiko handed Ayumu a long grabbing tool. Ayumu reached into the water with it and clasped the mysterious object. He pulled it up, placing it on the ground; it stopped glowing. It was a deep green orb; it seemed almost fuzzy.

"What is this thing...?" Ayumu wondered, poking it. Almost instantly, it broke open, like a coconut. Yumiko yelped; Hibiki stepped back in surprise. _Why did it—Ack!_ Suddenly, a bright blue-green snake-like creature leapt out of it without warning, burrowing into Ayumu's nose.

"AAAAHHHHH! WHAT THE HELL IS—!" Ayumu screamed, falling back. _...Oh my God!_ Everyone panicked. Yumiko ran up to him, catching him before he crashed into the floor. Suddenly, without warning, Ayumu's face twisted. A blade formed, and suddenly thrust into Yumiko's face; her blood splattered onto Ayumu's twisted face. He stood up calmly, looking around at everyone. _Oh my God! OH MY GOD!_ Kussaku was panicking.

"Ayumu—!" Hibiki called out before getting slashed in half. Suddenly, there was a flurry of movement; Ayumu's twisted face was slashing through the excavators.

"AAAAAAAAHHHHH!" Kussaku screamed, sprinting towards the tunnel. Somehow, he made it. He sprinted without a second thought towards fresh air. _WHAT THE HELL WAS THAT?! ACK, MY DAMN COAT!_ He threw off his restricting coat, clambering out of the tunnel into the freezing wind. The sun had set, and he could hardly see. _Don't stop, just run!_ He kept sprinting uphill, not daring enough to look back. He ran right past his trailer and kept running through the mountainous yet forested terrain until slowing to a stop from sheer exhaustion. _I'm exhausted...Can't run...Any longer...!_ He collapsed in the snow next to a large tree near a clearing on a small cliff facing west. His heart felt like it would burst out of his chest. _Did it follow me?!_ He looked around frantically, catching his breath; Ayumu was nowhere to be seen.

 _Whew...I made it...I'm alive...!_ Kussaku sighed in relief. He looked up at the sky just as snow began to fall lightly around him. He suddenly shivered from the cold. _I...I need to find warmth..._ He stood up. _I...I can't go back to the trailer...Ayumu—no, that...thing...could still be there. And that...'egg'. How many of them were there...?_ Kussaku trembled in apprehension at the thought. He looked out west and spotted a large structure in the distance. _Hope!_ He stood up and trudged slowly toward a way down from the cliff.

* * *

Seijū Niyani opened the door to his large apartment, stepping inside. He closed the door and tossed the bag on the table. He pulled out a sandwich from the bag and took a big bite before sitting down on the couch. He turned on the television to distract him, but the noise was simply a buzz in his mind. He couldn't sit still, either; he stood up almost immediately and began to pace.

After a few seconds, he threw down the sandwich and hurried over to his telephone. He quickly dialed his brother's number and called. _Come on, pick up, pick up!_ But his brother wouldn't pick up. Seijū threw the phone down and sat on the couch, his head in his hands. He had told his brother to call him every day, but it had been over a week with no word. Seijū sniffed, barely able to suppress his tears. What if his brother had been—

Knocking. Seijū heard knocking. He fell silent and looked hopefully at the door. The doorknob turned. The door creaked as it slowly swung open. Kussaku stood in the doorway, his soft face contrasting with his well-built body.

"Seijū...Seijū, I'm—" Seijū embraced Kussaku, tears streaming down his eyes. Kussaku paused in surprise, but ended up hugging Seijū back. "...I'm home, Seijū...I'm home..."

"Come on, let me get you...let me get you something to eat," Seijū suggested, letting go of his brother and turning toward the kitchen.

"...No. I'm not...hungry," Kussaku objected. Seijū paused, looking at his brother with confusion.

"Not hungry...?" He thought for a moment. "...What happened? Tell me you're alright! Are you—"

"I'm fine, but...I can't say the same for the other excavators," Kussaku said. He sat down on a chair; Seijū sat down next to him, taking a deep breath to calm himself down.

"Tell me what happened," he requested. Kussaku looked at the ground.

"You know what we were doing. I went with my team to the area just northeast of the city of Pripyat in the southern region of the Soviet Union. That spot held some promise."

"I know about that."

"But you don't know what happened next. As it turns out, we found a massive hot spring underground. The place was riddled with fossils—exactly what we had been searching for." His face sank. "The bottom of the spring seemed to glow, so Ayumu removed some sort of fuzzy green orb from the bottom. It looked like there were a bunch of them. It...it must've been some sort of egg." Kussaku trembled.

"...Egg...?" Seijū stuttered. Kussaku nodded.

"It...it hatched...! This weird snake, it...! It...it just dug into Ayumu's face...! It...He...He turned into a monster...! He...he...! He...killed them all! They're all dead!" Kussaku began to hyperventilate, hugging Seijū. After a moment, he calmed down. "I...I don't know what it was, but it was a m-monster...! I just barely got away with my life! I fled to the first place I saw...it was some power plant...I managed to get transportation from there...I'm so sorry I didn't call you earlier...!" Kussaku sobbed, falling to his knees. Seijū looked at him...and hugged him again.

"You're safe now, Kussaku...You're safe now..." Seijū whispered to him. It felt weird comforting his younger brother; Kussaku was usually the strong one, strangely enough. Kussaku stood up suddenly, wiping the tears from his eyes.

"Nowhere is safe from that..." Kussaku remarked. He then closed his fists tightly, lifting his head again. "I'm going back."

"What?! Are you crazy?!" Seijū yelled, shaking Kussaku by the shoulders. "That's suicide!" Kussaku shook his head.

"That thing...It killed my entire team! I can't just...I can't just forget that!" Kussaku blurted out. Seijū shook his head in disbelief.

"But—"

"The least I can do is find out what that thing is! To forget about that...would be spitting on their memory...!" He stepped towards the door, turning his head back. "Whether you come or not...That's up to you, Seijū." Kussaku smiled softly, waving back at him as he opened the door and stepped outside. Seijū stood there as he closed it. _Idiot!_ He felt a sinking feeling in his chest as he heard his brother's footsteps fading away. After a few seconds, however, he couldn't take it anymore. He sprinted out the door, leaving it open. Kussaku turned around and watched his brother run over to him. Seijū stopped next to Kussaku, panting.

"I'm...going...with you," Seijū panted. Kussaku looked down at him.

"Are you sure you—"

"I'm going with you!" Seijū proclaimed with more certainty. Their eyes locked for a moment. Kussaku nodded in silent understanding, and the two walked off.


	2. Chapter 2

"This is it," Kussaku said, pointing at his trailer. They trudged through the mud that had formed from the melted snow. Kussaku stopped next to the trailer, pointing at the tunnel in the distance. "It was down there."

"We can't just waltz in, though," Seijū pointed out. "You said you'd try and figure out what that thing is, but...How exactly do you plan on doing that?" Kussaku stood there in thought, scratching his head.

"That's a good question," Kussaku admitted. At that moment, they heard a crunch behind them. They whirled around. A man stood there with a serious, almost distant expression on his face. Seijū sighed in relief.

"Uh, hello...? Do you happen to know what happened here?" Seijū asked innocently. The man simply stared.

"Humans...?" he murmured in a monotone voice. Kussaku gasped, grabbing Seijū by the shoulder.

"Seijū! That's not a human! It's one of them!" Kussaku exclaimed, pulling Seijū back. Seijū stumbled behind the trailer just as the man's face began to twist in a spiral pattern. _What the—!_ Seijū began to panic in fear.

"What was that?!" Seijū exclaimed.

"One of them! Run!" Kussaku gasped, sprinting to the right. Seijū followed without hesitation, sprinting away. However, a second person cut them off. She wore the same facial expression. _Another one!_ Her face quickly morphed, and she prepared to slash at them. Kussaku dove out of the way, rolling downhill through the mud. Seijū followed, sliding down. Mud obscured his vision, although he could still see that thing standing behind him. Kussaku slid to a stop, catching Seijū.

They looked around; they had reached a dead end, save for the tunnel that burrowed into and under the mountain. They suddenly heard something behind them. One of them had followed them down to the tunnel. _Damn it, it's following us!_ Seijū stepped back into the tunnel; Kussaku pushed him in. Seijū turned around, heart pumping...just as blood splattered onto his face.

 _...No!_ Seijū gasped in horror. Kussaku looked at him, eyes wide. He then looked down at the blade that had pierced his chest. He looked back up at Seijū. _This can't be happening...!_ Kussaku opened his mouth to speak, but coughed out blood. _This...This can't be real...!_ The blade retracted from Kussaku's body, which collapsed on the ground, limp. Seijū screamed, panicked. The monster swung its blade at Seijū, who ducked towards his brother at the last moment. _Kussaku...! Come on, get up, Kussaku! GET UP!_ The blade sliced the bottom of Seijū's bangs, exposing part of his left cheek. _Please...Kussaku, don't leave me...!_ Seijū looked at Kussaku's emotionless face for a moment before coming to his senses.

Seijū whirled around and sprinted down the dark tunnel, tears streaming down his face. _Kussaku...That thing killed Kussaku...!_ He felt something prick his back, but hardly noticed it; his senses had dulled. He just kept running. _I...I won't let it get away with this...! But I...I can't kill it...!_ He nearly tripped over what seemed to be a coat. He entered a large open space, where he noticed one lone gas lamp in the corner. It was a hot spring...and a dead end. Corpses were littered all over the floor. He tried to find another way, but failed. _Damn it, there's no way out!_ He turned around, his back pressed against the wall. The monster entered the room, its head twisted beyond recognition. It's blades swung through the air. Seijū swallowed nervously. _Kussaku...I'll see you soon, don't worry..._

Suddenly, something splashed out of the spring. _What the hell?!_ Scalding water sprayed everywhere. A lanky humanoid figure, wearing only pants, had leapt out of the water, landing on its feet in front of Seijū. The monster paused.

"What are you doing?" it questioned calmly.

"I am curious as to how human emotion operates. I wish to keep this one alive for the purpose of observation," the newcomer explained, just as calmly. _Another one...?!_ Seijū trembled in fear. The monster scoffed.

"There is no reason for any of us to be interested in emo...wait."

A pause.

"Your human brain is still intact? Your parasyte was a failure, then," the monster deduced. _Parasyte? Is...is that what they're called?_ The newcomer shook his head.

"I wouldn't say that," he objected.

"If your human brain is intact, there is no reason you should be kept alive." Instantly, his blades sped into action...and were countered by other blades. Both of the newcomer's arms had extended into blades. The two of them instantly engaged into a rapid fight, their blades whirling all over the place. _They're fighting!_ Seijū quickly tried to think. _I need to get out of here...! But...but the only way out is through that hallway...! I need to get there, somehow!_ However, before Seijū could do anything, he heard a screech. He turned to look at the source; the monster had been decapitated! The decapitated head slowly crawled towards them, but was quickly chopped in half by the newcomer. He retracted his blades back into arms, turning towards Seijū.

"Hello," he said nonchalantly. _Now!_ Seijū screamed, taking this as an opportunity to escape. He sprinted towards the exit, but the tunnel was suddenly blocked off by a mass of flesh. _Ack!_ He turned around again; the newcomer had extended his arm to block the exit. "You shouldn't leave just yet."

"W-what are you?!" Seijū screamed out, shaking. The newcomer looked at him with a perplexed look.

"What am I...? Oh, you mean who! I'm Yūjin! Arms confuse you?" the newcomer introduced himself casually. "I'm not a parasyte, don't worry. I'm human, like you."

"H-HUMAN?! You have the gall to call yourself human?!" Seijū yelled, enraged. "You things, you...PARASYTES killed my brother!"

"Your brother...? ...Hey, you're bleeding." ...What...? Seijū became conscious of blood soaking on his back, being absorbed by his jacket. _Damn it, he's not lying! But...I have to ignore it!_ Seijū swung his fist at Yūjin, who evaded it easily. "Please don't."

"Or what?! You'll kill me too?!" Seijū countered. Yūjin shook his head.

"No. A parasyte may have killed your brother. That thing I just killed is a parasyte. Me? I'm a special case. You could say I'm a human with parasytes in my body," Yūjin explained.

"Why should I believe you...?!" Seijū argued. _That's impossible! Only a parasyte could do...that...with its arm!_

"Shouldn't my emotion be enough?!" Yūjin exclaimed suddenly, agitated. _Emotion...? ...Now that he mentions it...he does seem more emotional than the other ones..._ Yūjin breathed deeply. "I can explain this whole concept some other time, but right now I need to get you out of here."

"Why do you care about me...?" Seijū inquired. _It doesn't make sense._ Yūjin smiled.

"Because you're human." _Because I'm...human...I'm...human...!_ Yūjin retracted his hand from the exit. "I'll lead. Let's go."

Yūjin walked down the tunnel. _I might as well follow him._ Seijū reluctantly followed him into the tunnel. They walked down the tunnel until making it back to the entrance. Seijū paused in front of Kussaku's body. _Kussaku...That parasyte just...slaughtered you! I...I can't leave you here...!_ Refusing to abandon his brother, he threw the body over his shoulder. _I'm taking you with me!_ Yūjin looked at him.

"That's your brother?" Seijū nodded solemnly. "...I'm sorry."

 _I don't need your sym...Wait._ At that moment, Seijū noticed another 'parasyte' walking towards them.

"Yūjin, over there," he said, pointing at it. Before the parasyte could react, Yūjin had already sliced through it. _Whoa! That...That was fast!_ Yūjin trudged uphill towards the light; Seijū followed suit.


	3. Chapter 3

_At least you'll have a view of the sunset here._ Seijū placed a bunch of roses over the lump of dirt that served as Kussaku's grave beneath a large tree on a small cliff. Yūjin had tightly wrapped his back in bandages to stop the bleeding, although it was still painful. Seijū stood there solemnly under the tree for several minutes until Yūjin called him over. _...Goodbye...Kussaku._ Reluctantly, Seijū turned his back on Kussaku's grave and walked slowly toward Yūjin. He paused next to him.

"Tell me about parasytes," Seijū requested. Yūjin obliged.

"They're parasitic creatures that survive by burrowing into the brain of a human. They transform whatever part of the body they end up in into the parasitic equivalent, generally the head, with an identical appearance and voice, retaining all of the human's memories except the memory of emotion. They don't feel emotion. They can mutate whatever part of the body they took over, which is usually the head. They've been around for a while now, but after the disaster—I believe you modern people call it the Ice Age—most were killed. But not me!"

"Why's that?"

"Well, backtrack a bit. Back to my 'birth'...I'm the son of two parasytes," Yūjin revealed. _Wait...Damn it, you are one of them!_ Seijū gasped.

"Your parents were...!"

"Yeah. My parents were parasytes. I was born 'human', but I really wasn't. All I could do that hinted at my parentage was sense other parasytes. Strangely enough, I even felt emotion, unlike the parasytes. The thing is, almost immediately after my birth, a parasyte worm burrowed into my body. However, it failed." _So he's still like a human, huh...?_

"Why'd it fail?" Seijū asked.

"Because I was a parasyte. When it burrowed into me, it's consciousness and brain were killed, but it's capabilities fused with me and made me stronger. I'm a walking parasyte. Maybe I'm the only one who never had to kill a human to survive. I live like a human. Other parasytes even think my 'human' brain is still intact."

"So how'd you survive up until now?"

"I formed a sort of shield around me inside that hot spring. I was supposed to be protecting the eggs, but I ended up in a hibernation of sorts."

"Are you the only child of parasytes?"

"No, there were others," Yūjin revealed. "Although they preferred to live with humans. I don't know what happened to them, but chances are their descendants are among us today, capable of sensing other parasytes."

"How do you know all this, anyway? How can you even speak my language?"

"I'm a parasyte. There was one—a powerful parasyte that could transmit information telepathically to the rest. He was just born—probably the first one, calls himself Saisho. He did research, and transmitted his findings—including language—to all of us, me included, although I stopped receiving messages a little while ago." They both paused for a moment.

"Does you silence mean you're done asking questions?" Yūjin wondered. "I mean, seriously! With all the things you're making me explain, this would make a pretty boring story!" Seijū closed his fists determinedly.

"I'm going to kill them. I'm gonna kill every last one of them!" Seijū resolved. Yūjin laughed.

"You're just an ordinary human! How do you expect to fi—"

"You'll help me," Seijū decided, looking Yūjin fiercely in the eye. "You live like a human. You understand, don't you?" Yūjin looked at the ground, deep in thought. He looked up at Seijū after a moment.

"...You're right, in a sense. I do understand where you're coming from. So...well, I've decided to help. As long as I can live with you. Oh, and I never got your name," Yūjin said. Seijū nodded.

"...I'm Seijū Niyani. You can live with me. I should probably get an apartment in Pripyat. We can't leave the area; we've got to keep the problem contained."

"I agree. Let's go, Sei. Can I call you Sei?" Seijū nodded quietly. "I'll take that as a yes, Sei!" Seijū and Yūjin turned towards a large structure to the west.

"What is that place?" Yūjin questioned. "Saisho never said anything about it during the time I was receiving his messages."

"Oh, that's the Chernobyl Nuclear Power Plant. It's relatively new. Pripyat's just past it," Seijū replied. "Come on, we'll take the road around it."

* * *

Seijū tossed his bags down onto the ground next to the new apartment's bed. He crashed into bed, sighing in relief. A scab had already formed on the gash on his back.

"You seem rather relaxed for someone whose brother was just killed, Sei," Yūjin pointed out; he was standing next to the bed, still shirtless. Seijū looked up at him.

"That's because I know what killed him, and I—we—can kill it. There's no sense in crying about it," Seijū explained.

"Strange. I thought you to be the emotional type," Yūjin mused.

"Heh. Well, I've just come to terms with what happened, that's all," Seijū clarified. Suddenly, Yūjin froze. His expression grew more serious. "...Yūjin? What is it?"

"One of my kind is near," Yūjin said abruptly.

"...What?" Seijū asked, confused.

"One of my kind is near," Yūjin repeated. "Another parasyte. About three hundred meters from here." _That's right, he can sense them!_ Seijū sat up.

"They're here? In the town?" Seijū inquired.

"Obviously," Yūjin replied. "You want to kill him, don't you?"

"Of course!" Seijū stood up, but he faltered a moment later. "But...I'm just a human...! That's why I need you, Yūjin!"

"You don't seriously expect me to do all the fighting for you, do you?" Yūjin suddenly declared. Seijū froze.

"I...I can't fight...If I could, believe me, I would!" Seijū argued.

"You can," Yūjin stated simply.

"How? How do I—"

Yūjin covered Seijū's mouth, silencing him.

"He's extremely close. Ten meters," Yūjin whispered. "Find somewhere to hide for now."

Seijū nodded, and crept towards the kitchen. He hid under a cabinet, out of view from anywhere else. He listened in as Yūjin opened the apartment door.

"You seem to have settled in rather quickly," the parasyte greeted.

"Yes. This location was convenient," Yūjin responded, sounding much more apathetic. _Yūjin's talking with one of them...! What's to stop him from backstabbing me?!_ Seijū barely masked his increasingly panicked breathing.

"Your signal is unusual. Are you sharing a host with another parasyte?" the parasyte asked.

"Yes," Yūjin answered simply.

"Why have you never been to any meetings?" the parasyte inquired. Yūjin froze.

"Meetings...?" he mused. The parasyte's composure changed slightly.

"You're unaware of the meetings, and yet you are a parasyte...wait. Your brain is..." The parasyte paused. Instantly, Yūjin lashed out, although the parasyte countered it; it was expecting the attack. The two of them engaged in a fight so fast the blades were invisible. _They're fighting! But what if...what if Yūjin loses?! ...He said I could kill them...but how?_ Suddenly and unexpectedly, the parasyte knocked Yūjin to the ground. It poised to kill.

"NOOO!" Seijū screamed out, grabbing a kitchen knife and rushing towards the parasyte. _I have to try!_ Just as he attempted to plunge the knife into the parasyte's back, it knocked the knife to the ground and slashed at Seijū, cutting across his forearm. _AUGH!_ The parasyte turned towards Seijū, its blades gleaming in the light.

Suddenly, a blade pierced the parasyte's chest. Yūjin had stabbed the parasyte. _Yūjin...!_ Seijū sighed in relief. The blade retracted from its chest, and it collapsed to the ground, withering. _...Okay! You're alive, Seijū! Calm yourself...Keep calm...I'm okay..._ Yūjin looked at Seijū.

"Are you alright? Your arm is—"

"I'm fine," Seijū affirmed quickly, trying to ignore the pain. "Earlier, you were saying I can kill them. How?"

"It's simple. We have several weaknesses," Yūjin began. "First, there's our host body. Our host body is human, and we get our nutrients from the human blood. So we would die from a loss of blood, just like any other human. Therefore, an effective method to kill us would be to pierce our hearts or cut open our major arteries."

"Simple enough."

"Not necessarily; getting to the heart and successfully piercing it can be a challenge. Furthermore, there are other methods."

"Such as...?" Seijū urged.

"Fire. When exposed to fire, our cells panic; we could potentially fall apart on a molecular level. Ergo, an ideal weapon would be a flamethrower, although a match works just as well." _Well, that seems pretty effective._

"Are there any other weaknesses?" Seijū asked. Yūjin nodded.

"We are also weak to alcohol. Alcohol puts our cells in a state of shock, making us vulnerable. Large amounts of alcohol can even kill us. That's it for our weaknesses, though," Yūjin concluded. "I would personally recommend for you to acquire a flamethrower." _Is he serious?_

"And how do you suppose I do that?" Seijū inquired almost sarcastically. Yūjin shrugged.

"Steal one? Build one? Up to you, really." _Great. ...Wait. Actually, building one might not be a bad idea._

"I'll build one. Shouldn't be too hard; I mean, I am a mechanical engineer, after all. Just...help me out, will you? Make it easier?" Seijū requested.

"Sure. But be aware that we may have another...visitor. What concerns me is the 'meeting' he mentioned. That means they've organized. They may be sending more here," Yūjin warned. Seijū shrugged.

"Not a problem. I've got you, right?" Seijū remarked.

"Well, I guess so," Yūjin conceded.

"Then that shouldn't be a problem! Let's get started now, shall we?"


	4. Chapter 4

_There!_ Seijū looked down at his newly constructed handheld flamethrower. It was built using simple household items, like aluminum foil, staples, cans, and the like. The only things he needed to buy were canisters of propane gas to serve as fuel. He looked up at Yūjin, who stood next to him. He had pulled on a white shirt and trimmed his hair, his hands in his pockets.

"I didn't realize you knew engineering so well," Seijū remarked. Yūjin smirked.

"I'm a parasyte, remember? I learn stuff extremely quickly. I even think faster than you, Sei!" Yūjin pointed out. _Show-off._

"At any rate, the flamethrower's done. Let's go," Seijū decided.

"Go where?" Yūjin asked as Seijū stood up.

"Where do you think? We're going parasyte hunting." After having slung a belt of propane canisters over his shoulder and pulled a backpack onto his back, Seijū walked towards the front door.

"You're serious about this, aren't you? Well, what's your plan, anyway?" Yūjin inquired. _Plan?_ Seijū stopped.

"Er...We can just drive around until...until you receive a signal from a parasyte," Seijū stammered. Yūjin thought for a moment.

"Actually, that may not be such a bad idea," Yūjin agreed. "Oh, and you should take this as well." He handed Seijū a liter of water.

"What's the water for?" Seijū wondered aloud.

"In case you catch fire!" Yūjin winked jokingly at Seijū, who sighed.

"Let's go."

* * *

"Stop the car," Yūjin ordered. _A parasyte?_ Seijū pulled up the rental car to the side of the road, stopping.

"Did you detect a parasyte?" Seijū questioned. Yūjin nodded.

"It's 150 meters away. 135 meters. 120 meters. It's moving fast; it's probably in a car," Yūjin deduced. Seijū opened the car door, stepping outside the car and onto the street. Yūjin followed. "What are you doing?"

"If it's coming at us in a car, I'll hail down the car," Seijū said.

"That's stupid. It'll either ignore you or run you over!" Yūjin objected. _Huh? Movement in my peripheral vision..._

"Too late now," Seijū revealed. Yūjin turned around. A car sped towards them. _Alright, here goes nothing. Worst case scenario, Yūjin can save me._ Seijū waved his arms at it. However, it didn't slow down. On the contrary, it sped up. _Damn it!_ ...Yūjin, you're up.

Yūjin put his arm out, morphing it into a powerful claw. The car smashed right into his hand; the entire car was crushed by the force of the impact. Several shards flew into the air, landing around Seijū. _Phew, that was pretty impressive._ Something knocked open the car door, and a person—rather, a parasyte—stepped out of it, calm as ever.

"Why did you stop me? Do we not have a meeting to attend?" the parasyte questioned.

"No. We don't have a meeting," Yūjin retorted. He attacked the parasyte; the two of them engaged in combat. _Alright, then. I'll use my flamethrower only if absolutely necessary; I need to preserve my propane. If he needs me, I'll—wait, what was that?_

The other door on the car flew off. A figure climbed out of the car. _Shit! Another parasyte! Yūjin, are you—!_ Yūjin was still fighting the first one. _What do I—that's right, the flamethrower!_ With trembling fingers, Seijū pulled the trigger on the flamethrower. Flames burst from the nozzle for a few seconds before Seijū stopped firing. Instantly, the parasyte wailed. It split in half and fell to the floor in a heap, struggling to pull itself together. _It...It worked...!_ Seijū pulled out a knife and repeatedly slashed at the heap. _Die, die, die!_ After a few seconds, the heap began to wither. The parasyte was dead.

 _I...I did it! I killed a parasyte!_ Seijū sighed in relief, lowering his weapon. To his right, he saw Yūjin finally stab the other parasyte in the chest. He slashed it into multiple pieces, killing it. Yūjin turned towards Seijū; his eyes widened slightly when he saw the withered heap on the floor.

"There was another one? And you killed it?" Yūjin asked, surprised.

"I did it...! I killed it!" Seijū exclaimed excitedly. _Yes!_

"I take it the flamethrower did the trick?"

"That's right!" Seijū confirmed. "You know what this means, right?! These things aren't invincible! We can take 'em!"

"So now what? You've proven it to yourself. What now?" Yūjin asked.

"What do you mean 'what now'? We keep going! These are just two of them!" Seijū declared. _These damn parasytes are gonna pay for what they did to Kussaku! Every last one of them!_ He threw open the car door and sat in the driver's seat. "What are you waiting for, Yūjin?! Let's go!"

* * *

 _Damn it, where are they?! It's like they've just disappeared!_

"Yūjin, where are they?!" Seijū yelled out of frustration. Yūjin didn't even flinch. He thought for a moment before replying.

"Did you stop to think for a moment that maybe there simply aren't that many parasytes?" Yūjin pointed out.

"Of course I did! Kussaku...He said there were a bunch of eggs, not just one! Those eggs had to have gone somewhere!" Seijū explained. He turned left.

"But you can't live the rest of your life hunting down parasytes! I didn't know your brother, but I'm sure he wouldn't have wanted this! Plus, what if—" Yūjin argued before stopping mid-sentence.

"What is it? You detected another one?" Seijū asked. Yūjin didn't respond; he seemed flabbergasted. "...Hey, Yūjin."

"No...Not exactly," Yūjin muttered enigmatically. _Not exactly?_

"What do you mean?"

"There's...more than one...There are...way more than one...!" Yūjin stuttered. _More than one? Wait...Is this...the meeting...?_

"...How many?"

"There are so many I-I can't tell!"

"Where?"

"Three hundred meters ahead, but—"

Seijū slammed on the pedal. The car sped down the street.

"What are you doing?!" Yūjin exclaimed.

"Following the signal. If they're meeting, then we've got them all together, so hunting becomes much easier," Seijū explained as he sped towards a large office building at the end of the street.

"No!" Yūjin shouted, grabbing the wheel and swerving out of the way. His arm twisted; he also pressed on the breaks. The car skidded to a halt on the sidewalk.

"Why'd you—!"

"You can't fight that many! They'll kill you in an instant!" Yūjin yelled.

"Like they did to Kussaku?!" Seijū countered. "Look, if I have a chance to avenge him, I will, with or without you!"

"But—"

"You're not even human! You're a parasyte, for God's sake! I don't know why you haven't killed me yet, but I'm not gonna let you stop me from killing the other ones!" Seijū roared before stepping out of the car, slamming the door. Yūjin just sat there, processing what Seijū had said.

 _I don't need that thing! Yūjin may seem human, but he's just a parasyte!_ Seijū stomped down the road towards the building. _Here it is._ He tried the bottom door; surprisingly, it opened. Seijū stepped inside; the door swung shut behind him.

 _It's surprisingly dark. But I can still see, so whatever...So what now?_ Seijū crept through the lobby towards the front desk. _Hm? A directory?_ He picked up a directory from the front desk. _Maybe this'll have something useful._ Seijū perused the directory until stopping on the fiftieth floor. There was a massive conference room there that could apparently fit up to one hundred people. _Here! They're probably here!_

After leaving the directory on the desk, Seijū headed for the elevator. He tried the button; the elevator door slid open. _Alright, here I go._ Seijū punched in the floor number, and the elevator began to ascend. _Tenth floor...Twentieth floor...Thirtieth floor..._

 _Fiftieth floor!_ Seijū exited the elevator. To his surprise, the lights were lit on this floor. He stepped outside and crept towards a nearby door. He pressed his ears on the door and heard voices. _This is them...They're on the other side of this door...!_


	5. Chapter 5

Seijū exited the elevator. To his surprise, the lights were lit on this floor. He stepped outside and crept towards a nearby door. He pressed his ears on the door and heard voices. _This is them...They're on the other side of this door...!_

"...Why do we even need to do this?" a voice asked.

"I agree. It seems pointless. I, for one, deem releasing the spores unnecessary," another voice agreed.

"It amazes me that you fail to understand my reasoning," a familiar voice said. _That voice...! It...Isn't that Ayumu?!_ Seijū took a deep breath to calm himself.

"It's interesting, is it not? We are beings of pure logic, and yet we can disagree so strongly on such a simple topic," Ayumu continued.

"Does that matter?" a third voice chimed in. "All that means is that different chains of logic, each one as valid as the others, all exist simultaneously, and each one being thought about becomes more likely the more beings there are to think about it."

"Regardless, as living beings, we need some form of guarantee that our kind will not go extinct. That is a basic law of life," Ayumu explained.

"We are the guarantee, Saisho. We do not need more of us; we are immortal. In the case that our host body begins to die, we can simply switch hosts," yet another voice argued. _Saisho? But that's Ayumu...Wait! What if...Saisho's host...is Ayumu...!_ Seijū took another deep breath.

"Not necessarily," another parasyte replied. "You say we are immortal, and yet, several of us have already been killed. Ergo, we're not immortal. What if more of us were to be killed? We need a true guarantee, and Saisho's proposal is perfect. The eggs—or 'spores', as Saisho refers to them—will reside in the atmosphere for several years before coming down. By the time they come down, we will have already produced more spores to launch. If we were to die before they arrive, they can simply restart."

"Well said," Saisho complimented. "Perhaps the human listening to us will understand our motivations now." _Shit, they know I'm here!_ Seijū's heart jumped, and he could no longer hide his breathing. Something tore the door off its hinges. _ACK!_ Seijū stood there trembling.

"Hello, Seijū Niyani. That is your name, is it not?" Saisho greeted. _He knows my—!_

"How do you—"

"Parasytes retain the memories of their human hosts, and I distinctly seem to recall my host being introduced to you by Kussaku Niyani before going on his final excavation. Kussaku Niyani is your brother, is he not?" Saisho explained. _Kussaku...You dare mention his name?!_

Without hesitation, Seijū lifted his flamethrower and pulled the trigger. However, only a tiny flame emerged, and it withered away instantly. _Shit! I forgot to replace the canister!_

"A flamethrower? Not bad," Saisho remarked. "I don't need you alive; you'll be a hindrance. Kill him."

Instinctively, Seijū swung around out of the doorway. He turned around; numerous blades had slashed where he had been standing moments before. _Damn it!_ Seijū frantically tried to replace the canister using a new one from his belt of canisters. Just as he inserted it, several parasytes stepped out of the room. Their faces were contorted beyond recognition, and their blades pointed in Seijū's direction.

 _...Alright, it's ready!_ Seijū fired the flamethrower. Flames spewed out, burning the parasytes. They almost instantly collapsed to the ground. Seijū burned them a little longer. They melted into a pool of red goo, which quickly turned gray. _Got you!_

Seijū stepped into the conference room, shooting flames all around him. He killed maybe ten parasytes before the flamethrower ran out of fuel again. _Damn it, not again!_ Suddenly, a blade knocked the flamethrower to the ground. Seijū looked up; the blade came from Saisho's arm. _What the—! But he took over Ayumu's brain, didn't he?! So why can he do that with his arm?! Ack!_ Seijū dove out of the way of another blade slash, crashing to the ground. He noticed the blade had cut his hand.

"Goodbye, Seijū Niyani." _It's over!_ Saisho lashed out at Seijū. Suddenly, a figure leapt down in front of Seijū, deflecting the attack. He turned his head towards Seijū. _Y...Yūjin...! You saved me!_

"Don't run off without me again!" Yūjin scolded.

"Interesting. A rebel parasyte," Saisho remarked. "And a unique one at that. This will be interesting." Saisho and Yūjin engaged in combat immediately. _Damn it, he can't fight Saisho and defend me from the other ones! ...Oh! I forgot about that!_

Seijū reached into his bag as the other parasytes approached him. _Take this!_ He pulled out a bottle and threw it at them just as they attacked him. The attack destroyed the bottle, soaking them in alcohol! It splashed everywhere; they began to writhe in agony. _It worked! Alright, here goes nothing!_ Seijū pulled out his knife and ran in a circle, slicing through each one of them. _Take some more!_ He threw another bottle at the roof; more alcohol sprinkled on some others. _Alright, now's my chance!_ He used the distraction to run over to his flamethrower and reload it. He stood up just as the parasytes began to reorient their thoughts. He pulled the trigger; the flames spewed out furiously, igniting the alcohol. A massive blaze erupted in the room around the windows; nearly every parasyte in its vicinity seemed to react to it.

Seijū turned around; at that moment, Saisho smashed into Yūjin, knocking him into Seijū.

 _WAAAAH!_ Seijū's body crashed through the fire into a window, breaking right through it! _The windowsill!_ Seijū reached for the windowsill, but he had gone too far; his hand brushed it, but failed to get a grip. _Shit!_

"YŪJIIIN!" Seijū screamed as he plummeted down. _AAAAAUGH! ...Oh, shit!_ Seijū suddenly became aware that he was on fire. _Shit, the propane'll—!_ Seijū threw off the propane belt, hurling it away. He did the same with his bag, full of alcohol bottles. He pulled off his burning jacket and threw it away from him. He turned his head; the ground was rapidly approaching. _There's...no surviving this...!_

Suddenly, something grabbed him and pulled him into a window. He crashed into the ground, rolling for several meters before slowing to a stop. _What the hell?_ Seijū quickly clambered to his feet. Yūjin stood next to him, grinning despite the numerous bleeding cuts on his body.

"How'd you—"

"I leapt down and caught you. I swung into the window, using my body as a shield to protect you from any glass," Yūjin explained.

"...Thanks," Seijū sighed.

"Don't thank me! You were stupid! You could have died!"

"But I didn't!" Seijū objected. He took a deep breath. "On the contrary, now we know what we're up against, Yūjin." Yūjin's face suddenly grew more serious.

"About that..." Yūjin mumbled.

"What?" Seijū asked.

"Saisho...I believe he's the one who organized the parasytes," Yūjin began. "But he's not like the others. He's...more like me." _More like you? But...He took over Ayumu's body. He can't be like you._

"What do you mean?" Seijū inquired.

"Saisho seems to have multiple parasytes inhabiting his body, although I can't say how many," Yūjin revealed. _Multiple parasytes in one body...? Is that even possible? How does he control them all?_ "He essentially has all the same capabilities as me, although he can always transfer to another host if something goes wrong."

"But...you can beat him, can't you?" Seijū wondered.

"Yes, theoretically. But...You saw how our fight went. He...I don't know how, but he's faster than me, he's stronger than me, he can predict my every move...My attacks didn't even do anything. It's almost like he's invincible..." Yūjin explained.

"But...No parasyte's invincible! Surely, you can kill him, right?" Seijū argued. "...Right?!"

"I...I don't know..." Yūjin admitted. Suddenly, a parasyte swung in through the broken window. _Whoa!_

"Watch out!" Yūjin exclaimed, lashing out at the parasyte. He cut right through it. "It's dangerous to stay here, Sei! We need to go!"

"Yeah," Seijū said absentmindedly. Yūjin put Seijū on his shoulders and leapt out the window, falling three stories to the ground. He sprinted over to the car, getting in the driver's seat himself. He tossed Seijū into the passenger seat and slammed the accelerator. The car sped down the road. Seijū glanced in the mirror; not one parasyte could be seen.


	6. Chapter 6

"From what you explained, it sounds like Saisho wants to release parasyte spores into the atmosphere to guarantee the survival of parasytes as a species," Yūjin recapped. They were in the apartment.

"Yeah, that's the gist of it," Seijū affirmed as he pulled on a new jacket.

"In order to launch a substantial amount of spores into the atmosphere, one would need some sort of launching device," Yūjin concluded. "Am I wrong?"

"I guess not," Seijū said, looking in the mirror as he brushed his long bangs to the left. "They'd also need some way to create said spores. After all, they can't reproduce normally, or the result would be another parasyte like you, right?"

"Correct. They'd need to make a copy of their DNA and inject it into a hollow spore; in other words, the spores themselves are artificial. This bit of information, coupled with the necessity for a launching device, leads me to conclude that they must be operating out of a large laboratory, the likes of which is most likely hidden underground," Yūjin deduced.

"But to copy that much DNA in a short amount of time, all the parasytes would have to be in the lab at once," Seijū assumed. "So all we have to do is find the lab and destroy the equipment before they can use it! I mean, they've had two months since Saisho took over Ayumu's body to build it, so if we destroy it, that gives us two months to hunt and kill the parasytes."

"Maybe not," Yūjin interjected. "For all we know, they haven't even begun to build it yet, or maybe they didn't start until a week ago. We don't know how fast they work. However, regardless of what scenario it is, they surely have a location already. We just need to find that location."

"And how do we do that?" Seijū asked. Yūjin thought for a moment.

"We head back over to their meeting place. Surely, they must have some sort of plan there if they were able to meet there, assuming Saisho or one of the other parasytes didn't already retrieve it," Yūjin decided.

"What if they have retrieved it? What then?" Seijū said.

"We'll have to take our chances. It's either that or nothing," Yūjin explained.

"Alright, then. Plus, that has the added bonus of me recovering my flamethrower. Speaking of which, I need to restock on propane and alcohol to fight these parasytes," Seijū added.

"I went through the liberty of doing that for you," Yūjin revealed, walking over to a cabinet. He opened it; inside was a belt of propane cans and several bottles of alcohol. _Well, that's convenient._ Yūjin handed Seijū an empty backpack; Seijū filled it with bottles of alcohol and slung the propane belt over his shoulder, pulling the bag onto his back.

"Let's go."

* * *

"We're here," Seijū announced as he stopped the car on the side of the road. He and Yūjin stepped out of the car. Seijū looked over at the building. _The window hasn't been replaced yet. I guess the parasytes don't really care about things like that, huh...?_

"We'll split up to maximize efficiency," Yūjin planned.

"No!" Seijū countered. "That's a bad idea! Without you, I don't have anything to defend myself with!"

"Yes, you do, Sei. You have alcohol bottles and a knife, and you'll soon have your flamethrower. You'll be fine," Yūjin reassured. _...Yeah, I guess he's right._ "We'll meet in the lobby in exactly one hour."

"Agreed." The two of them stepped inside; the door was still unlocked. Yūjin entered the stairwell; Seijū opened the elevator and stepped inside. After pressing the buttons, he had but to wait. _Wait a second. What happens when we do find the lab? Obviously, we'll need to stop them from releasing the spores. But...How? How will we know what machinery to destroy? How will we destroy it? Can we destroy it? Plus, if all the parasytes are there like I suspect, then it'll just be what happened here all over again. What'll we do then...?_

The elevator slowed to a halt; the door slid open. _This is it._ Seijū stepped outside the elevator and into the conference room. The place was completely charred from the fire from before. Seijū scoured the floor for his flamethrower. _Over there!_ He walked over to his flamethrower and picked it up, refueling it immediately.

"You've returned? That was unexpected," a voice greeted. _Ack!_ Seijū whirled around. A parasyte stood by the doorway. "Saisho sent me back to retrieve the blueprints, but it seems you've returned. Did you, by any chance, find them?"

"...Blueprints?" Seijū wondered aloud. _...Damn it, I said that out loud! He probably wanted to know if I had given them to Yūjin, but now he knows the truth...!_ He pulled the trigger on his flamethrower; however, the parasyte sidestepped, avoiding the cone of fire. He lashed out at Seijū, knocking the flamethrower to the ground. _Shit!_

"AUGH!" Suddenly, after a brief moment of intense pain, his senses went numb. Seijū looked down at his chest. _No...way...!_ The parasyte's blade was stuck in his chest. _He...got me!_ The blade withdrew, and the parasyte regained its human appearance. _I can't...move..._ Seijū fell to the ground, too weak to stand. His vision had become hazy.

In a blur of movement, Yūjin stepped into the room and seemingly decapitated the parasyte. He ran over to Seijū and started saying something. Seijū tried to respond, but couldn't. He started seeing black spots which slowly expanded into an abyss of darkness.


	7. Chapter 7

_Ow!_ Seijū opened his eyes with a jolt. He was laying on his back in the conference room. Yūjin stood over him with a determined expression. Yūjin's arm was extended. _What the hell?_! Yūjin's hand was inside Seijū's chest!

"What the—"

"Calm down, Sei! Give me a moment!" _CALM DOWN?! YOUR HAND IS INSIDE MY CHEST!_ Yūjin's hand slowly disconnected from Seijū's chest, retracting back into a normal arm, leaving behind scarred tissue on his chest, surrounded by his bloodstained shirt and jacket.

"What the hell did you do to me?!" Seijū exclaimed loudly.

"I saved your life! You were stabbed, Sei! In your left lung!" Yūjin replied. _That's right...That parasyte plunged its blade into...!_ Seijū shivered violently at the memory. _I was dead...!_

"What did you do...?" Seijū asked.

"I integrated some of my cells into your lung to help rebuild it and hold it together," Yūjin explained. "It saved your life."

"...Thanks," Seijū finally said. _Stay calm, Seijū...At least you're alive at all..._ "So...about the blueprints..."

"So they are blueprints, then," Yūjin interrupted. "Yeah, I found them. On another floor. I came up here to let you know, but..."

"I was stabbed...Right," Seijū finished. "Can I see them? The blueprints."

Yūjin nodded, pulling a folded up packet of papers from his pocket and handing it to Seijū. _Alright, let's see..._ Seijū unfolded the papers and spread them out on the table. _Wow, these blueprints are extremely detailed!_ Seijū scanned the blueprints. There seemed to be a lot of strangely designed chambers with unusual devices in them. There was a 'control room' and a 'launch room'; the launch room seemed to contain some sort of device intended to launch the spores. _What's this?_ The power room was strangely designed. It didn't generate its own power; it was more like it siphoned power from another source above it.

"...Clear power..." Yūjin murmured to himself, barely audible.

"What?" Seijū asked.

"I said 'Chernobyl Nuclear Power Plant'. Look there," Yūjin repeated pointing at a corner of the paper. It read 'Chernobyl Nuclear Power Plant'. _Of course!_

"This facility's underneath the Chernobyl Nuclear Power Plant!" Seijū exclaimed.

"Isn't that the large structure near the excavation site?" Yūjin inquired. Seijū nodded.

"It seems like Saisho's siphoning nuclear power from the plant to power his facility," Seijū revealed. "We need to head over there now; we can't risk his device fully charging."

"Without a plan?"

"Of course I have a plan! We'll infiltrate the control room and destroy the controls. Without those, they won't be able to launch the spores. From there, we can work our way through the place and destroy as much machinery as possible," Seijū summarized.

"And what if we encounter Saisho? What then?" _Damn it, he's right. Hmm..._

"...We have to fight Saisho at some point. Why wait for him to get stronger? We need to do this now," Seijū concluded. Yūjin thought for a few seconds before responding.

"...Okay. We'll head over now, then," Yūjin conceded.

* * *

"I hope you don't mind my stopping here; since the power plant's running a system test right now, we can't park too close, so I figured I'd stop by here," Seijū said as he stopped his car near the excavation site, by the large tree. The two of them got out of the car. _...Kussaku...Lend me your strength..._ Seijū's eyes drifted towards the lump of dirt that served as Kussaku's grave, lit up by the moonlight. It had slightly sunken in due to the mud, and the roses Seijū had previously placed on it had withered away and turned a colorless gray. _...Hey, what's that?_ A lily had sprouted from the dirt.

"Hey, Sei!" Yūjin called out. Seijū turned around towards Yūjin.

"Yeah...Yeah," Seijū answered absentmindedly. Yūjin pointed downhill.

"Look down there!" Seijū did as Yūjin instructed. A woman was walking into a more heavily forested area. _Could that woman be a parasyte?_

"We need to follow her! She might be heading toward the entrance!" Seijū exclaimed, leaping down and sliding down the slope.

"H-hey, wait!" Yūjin shouted, jumping down after Seijū. _Come on, come on, c—ouch!_ Seijū stubbed his toe on a rock at the base of the slope. _Where'd she—there!_ Seijū sprinted off towards the forest just as Yūjin reached the bottom of the slope. Seijū silently sprinted into the trees, slowing down as he neared the parasyte. _I can't go too fast; I can't let her notice me._ Seijū slowed to a crawl. He watched as the parasyte walked another ten meters or so. Suddenly, she stopped. _Is this it? The entrance?_

The parasyte bent over and opened a hatch that had previously been obscured from Seijū's vision by a large rock. _This is definitely it!_ Seijū stood up in the open and pulled the flamethrower' trigger; it spewed flames that burned the parasyte.

"OOOOURGH!" it wailed. Seijū pulled out his knife and lunged in, stabbing the parasyte in the heart. It wailed some more before falling to the ground in a heap. _That's one more do—SHIT!_ Seijū jumped back as a burning branch crashed in front of him. He looked up. _Dammit, I shouldn't've used the flamethrower!_ The trees around him had lit up in flames. Suddenly, Yūjin sprinted out of the brush and stopped next to Seijū, panting.

"Damn, you're fast!" Yūjin remarked before stumbling back. "The flames...They're hot..." _Shit! I need to do something, and fast!_ Seijū looked around frantically. _There!_ He helped Yūjin over to the hatch and tossed him in, jumping in behind him and shutting the hatch. Yūjin's face had mutated, and hung open. The rest of his body had been affected in a similar manner.

"Are you alright?! Yūjin!" Seijū shouted.

"...Yeah, just...Cells are freaking out...I need water..." Yūjin mumbled. _Water?! Where do I—! Oh, that's right!_ Seijū pulled out the liter of water from his bag and handed it to Yūjin, who instantly drank the entire thing. He dropped the empty liter bottle on the floor. His body slowly reformed itself into his human form.

"Er...How does that even work?" Seijū asked, astonished.

"Fire makes our cells freak out, but the nutrients in water help us regain control over our cells," Yūjin explained briefly. "At any rate, that doesn't matter."

"You're right," Seijū agreed. The two of them turned around and ran down the hallway.

"According to the blueprints, the control room is on the opposite end of the facility, above the power room," Yūjin recalled. "Turn right!" Seijū and Yūjin turned right...and encountered several parasytes.

"Ready?" Yūjin asked.

"I was about to ask the same thing." Yūjin lashed out at the parasytes as Seijū readied a bottle of alcohol. _Wait a second...! Have they...slowed down? They're going so slow I can see their individual movements...!_ Yūjin sliced through the last of them.

"You weren't very helpful," Yūjin remarked.

"Yūjin, did they seem a little slow to you?" Seijū inquired. Yūjin gave him a perplexed look.

"Slow? No, they're not any slower," he replied. _If you say so._ "Either way, we should keep moving." Yūjin and Seijū continued down the hallway, stepping over the corpses. Suddenly, another one stepped into the hallway. He had an arrogant look to him. Yūjin and Seijū paused.

"Well, hello there," the newcomer greeted. "You there. The tall one. You're a parasyte?"

"That's right," Yūjin replied. "Who are you?"

"Call me Tesuto. So tell me, tall one. Why have you betrayed us?" the newcomer said.

"It's not a betrayal if I was never on your side to begin with," Yūjin stated fiercely. He lashed out at Tesuto with his arm blade. Tesuto's face twisted apart, and a blade countered the attack.

"Is that all you've got?" Tesuto taunted. _What does he—What the hell?!_ Seijū gasped.

"How'd you—!" Yūjin stammered as he looked down at the blade that had pierced his side. _N-No way! I-I've never seen a parasyte other than Yūjin or Saisho use their arm like that!_ Tesuto smirked arrogantly.

"This host body..." Tesuto began, retracting the blade from Yūjin's side back into an arm. "This host body doesn't contain just one parasyte. It contains two!" _Two parasytes in one body...? Almost like Saisho..._

"That doesn't matter!" Yūjin exclaimed before lashing out with both arms. Tesuto promptly countered; the two of them engaged in a fierce fight. _Behind us!_ Seijū whirled around as three parasytes emerged from a hallway to the right. Their faces twisted almost immediately.

 _More of them!_ Seijū pulled out a bottle of alcohol and threw it at them. It shattered, dousing them in alcohol; they wailed wildly. At that moment, a fourth parasyte emerged from behind them. It readied its blades and lashed out at Seijū.

 _Shit!_ Seijū leapt out of the blade's path. _Thank God these things are slow today!_ Seijū pulled out his flamethrower and pulled the trigger. The first three ignited in a massive blaze; however, before he could burn the fourth one, it slashed at Seijū. _No!_ Seijū's face sank as his flamethrower clattered to the ground, having been sliced in half. The blade had cut through his jacket and the propane belt; the belt slid off his shoulder and landed on the ground.

 _Damn it!_ Seijū slid back, clenching his fists. The parasyte's blades lunged at Seijū once more. _My knife!_ Seijū pulled out his knife and deflected the blades. Before the parasyte could react, Seijū lunged at it. He leapt to the side, evading the blades again. _Now's my chance!_ Seijū slashed at the extended blade, cutting the limb clean off. It landed on the ground with a splat and shriveled up almost immediately.

"UUUUURGH!" the parasyte wailed, the pain evident in its voice. _An opening!_ Seijū sprinted towards the parasyte, plunging his knife into its chest. He pushed it up, cutting through several vital organs. _I did it!_ He pulled the knife out as the parasyte collapsed to the ground.

"AAAAUGH!" a voice suddenly screeched. _Was that—?!_ Seijū whirled around. _NOOOOOO!_

Yūjin lay on the ground, his hand clutching his chest. Blood seeped through his fingers. _Y-Yūjin...! Not you too...!_ Tesuto stood over Yūjin with a smirk.

"What did I tell you?! You couldn't possibly beat me!" Tesuto exclaimed victoriously. _No...!_ Tesuto laughed arrogantly.

"NOOOOOO!" Seijū yelled out. Tesuto turned towards him.

"You're still ali—" Seijū leapt at him with his knife. Tesuto's arm and face both mutated, launching several blades at him. Seijū deflected most of them, although one slash cut right through the strap for his backpack and his bangs, exposing his left eye. His bag crashed to the ground, the bottles of alcohol all shattering.

"DIIIIIE!" Seijū roared as he slashed right through Tesuto's arm into his chest. _DIE, DAMMIT, DIIIIIIE!_ He pulled out the knife and slashed numerous times. _YOU KILLED YŪJIN!_ Tesuto's limp body crashed into the wall, staining it red with blood. _Yūjin is...dead...!_ Seijū finally stopped slashing, tears welling up in his eyes. Suddenly, Tesuto twitched.

"A...A human...beat me...!" Tesuto sputtered. "Y-You think...You think this is over...? S-Saisho...I'm just a test...An experiment, but...Saisho's the final result...! He's got more...more than two parasytes...in his...body...He's...In...vin...ci..." Seijū plunged the knife into Tesuto's neck and slit it, ending his life. Seijū dropped the knife and sprinted over to Yūjin. _Huh...?_ His eyes twitched.

"Hey, Sei...Looks like he got me..." Yūjin coughed out blood.

"Yūjin, stay with me...! I can save you!" Seijū wailed.

"No...I'll be dead in just a minute..." Yūjin admitted.

"W-What are you...talking about?!" Seijū stammered, sobbing. "You'll live...! I know you'll live...!" Yūjin smiled softly.

"Y-Yeah, I'll live...I won't be fully dead..." Yūjin began, struggling to get each word out. "What you just did...Killing Tesuto...Should be impossible..."

"Yūjin, don't waste your breath...! Don't talk...Just breathe...!" Seijū sobbed.

"When I saved you...I integrated my cells with yours. Those cells...They're me...! I'll...live on in you...! I'll make you stronger...Faster...!" Yūjin coughed.

"Don't talk like that...Don't talk like that!" Seijū exclaimed, tears rolling down his cheeks.

"It's okay, Sei...My time is up. Just...Know that you...You've shown me...what it really means...to be...h..." _No...Nooo...!_ Yūjin's body went limp, his eyes hanging open. _Nooo!_

"NOOOOOOOOOOOO!" Seijū screamed. _YŪJIIIIIN! Yūjin! Yū...Yūjin...!_ Seijū collapsed on the ground, staring into Yūjin's unmoving eyes. He took a deep breath, slowly closing Yūjin's eyelids.

"...Yūjin...Rest in peace..." Seijū whispered to him, laying him down softly. He stood up slowly, clenching his fists. _First, they killed Kussaku. Now, they've killed Yūjin...These parasytes are heartless...!_ Seijū closed his eyes. _I...I can't let anyone else go through this...I won't let anyone else go through this! Those parasytes...Saisho needs to be stopped! I'll put an end to those parasytes if it's the last thing I do!_ Seijū opened his eyes.

"YOU HEAR ME?! YOU HAVEN'T WON! I'LL BE THE ONE TO FINISH YOU!"


	8. Chapter 8

_The control room is this way!_ Seijū made another right. A parasyte moved into the pathway.

"A huma—"

"GET OUT OF MY WAY!" Seijū roared, drawing his knife. He caught the parasyte by surprise, easily decapitating it. He sprinted further down the hallway before encountering two other parasytes.

Both of their heads twisted into blades that launched towards Seijū. _I can see each blade morphing in the air!_ Seijū parried the blades to his left and right, ducking under a third blade.

"He's fast!" one of the parasytes exclaimed, surprised. Seijū parried another blade to his left, and swung down his knife on one of the parasyte's ligaments, chopping off one of the blades. _Take this!_ Seijū hurled the knife directly at a parasyte's chest; the knife struck true, sending blood everywhere. Seijū spun around another blade, although a second blade caught him by surprise, cutting his abdomen. Seijū yanked the knife out of the parasyte's chest; blood splurged onto Seijū's body, but he didn't care. He slashed at the other parasyte, decapitating it. _That's two more down! ...Whoa!_

There was a sudden tremor that resonated throughout the lab. The tremor subsided after a moment. _Just a tremor...! Have to keep going!_ Seijū turned down the hallway in a sprint. _...A doorway! The control room!_ Seijū kicked down the door and leapt inside, knife at the ready. _...What?! No way! How could I make such a mistake?!_

The room was full of pipes and advanced mechanisms. _This is the power room...!_

"GOD DAMN IIIIIIIIT!" Seijū screamed. _...Wait! So...this room, it siphons nuclear power from the Chernobyl Nuclear Power Plant above, huh...Right about now, that plant is running a system test—a power failure experiment. That must be why the parasytes needed to do the launch now...! The alterations in the system they would have to make for the device to properly operate would be masked by the experiment!_

 _In other words, these pipes are full of nuclear energy right now. If they were to malfunction...The ensuing nuclear explosion would destroy this entire lab, including the launching device, and would kill all the parasytes; the explosion would obviously resonate in the above plant, but it'll seem like a failed test. As a mechanical engineer, I can make that happen easily._

Seijū quickly moved around the room, turning multiple valves until finally resting his hand on one. _All it takes at this point is for me to turn this last valve and the system should overload, resulting in the explosion. But..._ Seijū shivered. _But to do that...would kill me...and Yūjin's remnants along with me..._

"Hey, Sei," a familiar voice said. _No way—!_ Seijū whirled around.

"...YŪJIN!" Seijū exclaimed excitedly.

"Sei, it looks like we got the rooms confused," Yūjin pointed out.

"...Yeah, we did," Seijū confirmed.

"So what's your plan now? I'm not here to help you this time."

"Yūjin...I don't know!" Seijū exclaimed, tears welling up again. "I'm alone! You're gone, Yūjin! You're gone forever! I could just blow up this whole lab, but—!"

"You're afraid of killing the cells I integrated into your body? You're afraid of killing the last part of me?" Seijū nodded, barely able to hold back his tears. "...Sei. Sei, listen to me."

"I'm...I'm listening," Seijū sobbed.

"Sei, do you know the real reason why I died the way I did?" Yūjin asked.

"N...No..." Seijū muttered.

"I died to protect you, Sei. I could've simply joined Tesuto. But I chose to fight him instead to protect you. I was willing to die for you, Sei. I never intended for you to let Saisho win to protect me."

"But—"

"I'm a parasyte, Sei! No matter how you see it, I'm a parasyte. Don't you want to kill every parasyte anyway? I'm just another parasyte!" Yūjin argued.

"You're not just another parasyte, Yūjin!" Seijū shouted. "You...You were more than that...!"

"And so he was willing to die for you," another voice interjected. A familiar face emerged from behind Yūjin.

"K...Kussa...ku...!" Seijū stuttered, overwhelmed by his emotions.

"Seijū," he began, his soft face smiling as usual. "Yūjin was willing to die for you. A parasyte was willing to die for you! How many humans do you know that would die for you?!"

"I...I don't...know..."

"Do you want to know what really happened at the excavation site?" Kussaku continued. "That parasyte was looking at you, not me. It lunged at you, not me...I jumped in front of the blade to protect you, Seijū!" He paused. "And I was the only person in the whole world willing to do that for you!"

"Until you met me, that is," Yūjin added.

"A parasyte did something most humans wouldn't even consider, Seijū! He sacrificed himself for you! That makes him more human than the people you see every day!" Kussaku exclaimed.

"Those other parasytes...Saisho, Tesuto, all of them, they're all heartless monsters! It doesn't matter that they're parasytes, what matters is their hearts! You don't have to be human in body to be human in spirit, Sei, and I'm living proof of that! And them? They're monsters by choice, not necessity," Yūjin proclaimed.

"...What does...all that even mean...?" Seijū stuttered, choking on his words as more tears streamed down his face.

"What he's trying to say is that if you need to make a sacrifice, then just do it." Kussaku smiled at him. "We'll be waiting, Seijū."

"No...Don't leave me...!" Seijū wailed, reaching towards Kussaku. _No...!_ His hand went right through him as his image faded away. He looked right. Yūjin was gone, but Saisho stood at the doorway.

"Hello, Seijū Niyani," Saisho greeted.

"Saisho...!" Seijū growled.

"You blame me for all this, don't you? Your brother's death, and now that parasyte, too. You probably want to kill me," Saisho began. Seijū remained silent.

"No words? Am I to interpret that as hostility?" Seijū still remained silent. "Seijū, don't fight. It's over. As it is, you're unarmed, and your partner—Yūjin, I believe he called himself—is dead. You don't have anyone to defend you. Furthermore, the first test wave of spores has already been released." _W-Wha—! Don't tell me that tremor—!_ "A second, much larger wave will be released shortly. You've already lost."

"...Not yet," Seijū objected quietly.

"Not yet? Perhaps you're stronger than you let on? Or—ah, I see. Yūjin most likely integrated some of his cells into your body. Am I wrong?" Seijū refused to reply. "Even with that enhanced strength, I've integrated numerous parasytes into my body to focus solely on armoring my body, so I can focus completely on offense. I'm invincible!"

 _...These parasytes...They killed Kussaku...They killed Yūjin...And they're about to disperse even more of them across the globe. The test wave's already been released, but I can still stop the second wave...! ...Kussaku...Yūjin...Thank you for everything...!_

"...Nothing's invincible." Seijū turned the final valve. _...I'll see you soon...Yūjin...Kussaku..._ He slowly closed his eyes as he was engulfed by the warm and radiant light that brought his saga to a close once and for all.

* * *

Afterword

* * *

The Chernobyl Nuclear Power Plant's explosion, known as the Chernobyl Disaster, took place in April 1986. The test wave of parasyte spores was released into the atmosphere, where they drifted about for three years until the baby parasytes developed to the point that they became heavy enough for the spores to come down to Earth in 1989, where they landed in scattered locations across the globe. One such spore happened to land just outside the home of Shinichi Izumi.


End file.
